Legacy computer systems are continuously being replaced with newer, more effective computer systems in order to reduce costs and increase efficiency. After each new system is implemented, the data produced by the new system must be compared against the data produced by the legacy system. Any discrepancies between the two systems should be rectified before the new system can be put online and before the legacy system can be taken offline. Often the comparison of the data produced by the two systems may be performed manually. The data may be loaded into a spreadsheet and the values in the spreadsheet may be manually compared. Due to data volumes and resource limitations, only a subset of data is selected for comparison using this method. A manual comparison may require a significant amount of man-hours and may suffer from human error and, consequently, may result in deployment risk. Since legacy systems are often customized for a particular implementation, automated data comparison systems may not exist, or may not be capable of effectively comparing the data produced by the two systems.